People is pretty self-explanatory. To have a group you need more than one person and really at least five before it becomes sustainable. In most places anarchists are not very hard to come across, in most countries at least 1 in a 1,000 to 1 in 10,000 people might consider themselves an anarchist. So even in fairly small towns there are likely to be at least a dozen or so 'anarchists'.
Unfortunately the next step most groups take is to try and set up a group which includes just about everyone that adopts the label. This may seem like the logical thing but problems arise when we look at the next two requirements.
For a group to be effective it has to have a clear idea of what it is fighting for, not simply what it is fighting against. And it must agree what the best tactics are to use and that everyone in the group will use follow the agreed tactics. This will be discussed at length later
In order to function an organisation needs a paper, leaflets, rooms to met in, money for mailouts and a dozen other items that require lots of the green stuff. Ways of tackling this requirement include
The amount of work you do and the amount of money your willing to put in depends on you feeling good about the organisation. It is adversely affected if you feel you are being used, or that other people are not willing to contribute their share. That much is obvious. However its also true that your commitment will be dependant on how much you agree with what the group is doing/saying and whether the groups seems to be going somewhere or just treading water. It's easy to keep people around when lots of stuff is happening, the difficult thing is the periods in between bursts of activity.
I favour a high commitment oriented group over a 'as many people as possible' one. With time I think the high commitment one can come to involve a lot of people where as I don't think the reverse can be true. Enough background, here's some concrete ideas.
Find another four or five people that are willing to do something serious. You may know this many already if not get an address you can put on leaflets and start leafleting demo's etc. with anarchist stuff. Get a flag or a banner together. Maybe call a public meeting on anarchism and see who turns up.
Once you get your four or five people be prepared to spend a couple of years getting your act together before you start to expand. Agree on a membership levy and conditions of membership. Write down agreed perspectives and strategy for promoting anarchism and getting involved in activity. Start publishing a regular paper arguing these ideas. Sell it through bookshops, campaign meetings and demos. Get involved around struggles and develop respect for your group as good activists and people with good ideas. Don't concentrate on talking to anarchists, concentrate on talking to activists. Find out about the national groups and travel to nearby demos/ conferences. Make a banner you can bring on marches. I know all of this is possible with as few as five people because I spent the period from 1989-91 doing just that here.
Above all you need to be patient. A big problem is the 'revolution next year' syndrome where you hype yourself up to expecting a lot and then get disappointed when it does not materialise. Work out where you are going but be prepared to go there slowly, as I said above its likely to be two years before you get any serious return on your work.